Method of manufacturing semiconductor device

ABSTRACT

A solder  14  is formed, by a plating method, on a connecting surface  21 A and a side surface  21 B in a connecting pad  21  of a wiring board  11  which is opposed to a metal bump  13  formed on an electrode pad  31  of a semiconductor chip  12 , and subsequently, the solder  14  is molten to form an accumulated solder  15  taking a convex shape on the connecting surface  21 A of the connecting pad  21  and the metal bump  13  is then mounted on the connecting surface  21 A of the connecting pad  21  on which the accumulated solder is formed, and the accumulated solder  15  and the metal bump  13  are thus bonded to each other.

BACKGROUND OF THE INVENTION

The present invention relates to a method of manufacturing asemiconductor device, and more particularly to a method of manufacturinga semiconductor device in which a solder provided on a connecting pad ofa wiring board and a metal bump provided on an electrode pad of asemiconductor chip are bonded to flip chip connect the semiconductorchip to the wiring board.

Besides, for example, an Au bump or a Cu bump are used as the metalbump.

In some conventional semiconductor devices, a solder provided on aconnecting pad of a wiring board and a metal bump provided on anelectrode pad of a semiconductor chip are bonded to flip chip connectthe semiconductor chip to the wiring board (see FIG. 1).

FIG. 1 is a sectional view showing the conventional semiconductordevice.

With reference to FIG. 1, a conventional semiconductor device 100comprises a wiring board 101, a semiconductor chip 102, a metal bump103, a solder 104, an underfill resin 105, and a solder ball 115.

The wiring board 101 has a board body 106, a via 107, a connecting pad108, solder resists 109 and 114, a wiring 110, and a pad 112.

The board body 106 is a core substrate. As the board body 106, it ispossible to use a glass epoxy resin or a tape-like resin, for example.

The via 107 is provided to penetrate through the board body 106. Theconnecting pad 108 is provided on an upper surface 106A of the boardbody 106 in a corresponding portion to a position in which the via 107is formed. The connecting pad 108 is connected to the via 107.

The solder resist 109 is provided on the upper surface 106A of the boardbody 106 to expose the connecting pad 108. The wiring 110 is provided ona lower surface 106B of the board body 106 in a corresponding portion ofthe position in which the via 107 is formed. The wiring 110 is connectedto the via 107. Consequently, the wiring 110 is electrically connectedto the connecting pad 108 through the via 107.

The pad 112 is provided on the lower surface 106B of the board body 106.The pad 112 is connected to the wiring 110. The solder resist 114 isprovided on the lower surface 106B of the board body 106 to expose thepad 112.

The semiconductor chip 102 has a plurality of electrode pads 116. Theelectrode pads 116 are electrically connected to an integrated circuitprovided on the semiconductor chip 102. As a material of the electrodepad 116, it is possible to use A1, for example.

The metal bump 103 is provided on the electrode pads 116. The metal bump103 is provided in contact with the connecting pad 108. Consequently,the semiconductor chip 102 is electrically connected to the connectingpad 108 through the metal bump 103.

The solder 104 is provided on the connecting pad 108. The solder 104serves to fix the metal bump 103 onto the connecting pad 108. As thesolder 104, it is possible to use an Sn solder or an Sn based alloysolder which is formed by a nonelectrolytic plating method, for example.The solder 104 formed by a plating method as well as the nonelectrolyticplating method includes a large number of fine voids. In the case inwhich the Sn solder or the Sn based alloy solder is used as the solder104, it is preferable that a thickness should be equal to or smallerthan 1 μm, for example. By reducing the thickness of the solder 104,thus, it is possible to prevent the Sn contained in the solder 104having the fine voids from being diffused into the electrode pad 116through the metal bump 103, resulting in a non-conduction between theelectrode pad 116 and the metal bump 103 in a heat treatment in aformation of the solder ball 115 (a heating temperature is approximately230° C. to 260° C.) or a high temperature inspection of thesemiconductor device 100.

The underfill resin 105 is provided to fill a clearance between thesemiconductor chip 102 and the wiring board 101. The underfill resin 105serves to compensate for a connecting strength between the semiconductorchip 102 and the wiring board 101.

The solder ball 115 is provided on the pad 112 of the wiring board 101.The solder ball 115 is an external connecting terminal for electricallyconnecting a mounting board (not shown) such as a mother board and thesemiconductor device 100.

FIGS. 2 to 7 are views showing a process for manufacturing theconventional semiconductor device.

With reference to FIGS. 2 to 7, description will be given to a method ofmanufacturing the conventional semiconductor device 100. First of all,at a step shown in FIG. 2, the wiring board 101 is formed by awell-known technique. At a step shown in FIG. 3, subsequently, thesolder 104 is formed on at least the upper surface of the connecting pad108 by a nonelectrolytic plating method. A thickness of the solder 104is set to be equal to or smaller than 1 μm. For the solder 104, forexample, an Sn solder or an Sn based alloy solder is used.

At a step shown in FIG. 4, next, the metal bump 103 is formed on theelectrode pads 106 provided on the semiconductor chip 102. At a stepshown in FIG. 5, then, a high pressure is applied to cause the metalbump 103 to come in contact with the connecting pad 108. Thereafter, thesolder 104 is subjected to a reflow. Thus, the connecting pad 108 andthe metal bump 103 are electrically connected to each other.

At a step shown in FIG. 6, next, the underfill resin 105 is formed tofill the clearance between the semiconductor chip 102 and the wiringboard 101 by a capillarity.

At a step shown in FIG. 7, subsequently, the solder ball 115 is formedon the pad 112 of the wiring board 101 in a state in which the structureshown in FIG. 6 is heated. Consequently, there is manufactured thesemiconductor device 100 in which the semiconductor chip 102 and thewiring board 101 are flip chip connected to each other (for example, seePatent Document 1) [Patent Document 1] JP-A-8-148496

In the conventional semiconductor device 100, however, the solder 104having a small thickness (1 μm or less) is formed on the connecting pad108 and is bonded to the metal bump 103. For this reason, there is aproblem in that the bonding portion of the solder 104 and the metal bump103 is broken, resulting in a deterioration in an electrical connectingreliability between the wiring board 101 and the semiconductor chip 102due to a difference in a coefficient of thermal expansion between thewiring board 101 and the semiconductor chip 102 when a temperature ofthe solder 104 subjected to the reflow is lowered to a room temperature.

In the case in which a material of the substrate body 106 is soft (forexample, a tape-like resin) or the case in which the structure of theelectrode pad 116 is fragile, moreover, it is hard to cause the metalbump 103 to come in contact with the connecting pad 108 in a state inwhich a high pressure is applied. Therefore, there is a problem in thatthe electrical connecting reliability between the wiring board 101 andthe semiconductor chip 102 is deteriorated.

In the case in which there is a variation in a height between the metalbumps 103 or the case in which a warpage is generated on the wiringboard 101, furthermore, the solder 104 does not come in contact with themetal bump 103. For this reason, there is a problem in that the metalbump 103 cannot be electrically connected to the connecting pad 108.

SUMMARY OF THE INVENTION

Therefore, the invention has been made in consideration of the problemsand has an object to provide a method of manufacturing a semiconductordevice which can prevent Sn contained in a solder from being diffusedinto an electrode pad of a semiconductor chip through a metal bump andcan enhance an electrical connecting reliability between a wiring boardand the semiconductor chip.

According to a first aspect of the invention, there is provided a methodof manufacturing a semiconductor device including a semiconductor chiphaving a plurality of electrode pads and a wiring board having aconnecting pad which is opposed to the electrode pads,

a metal bump provided on the electrode pads being bonded to a solderprovided on the connecting pad, to flip-chip connect the semiconductorchip to the wiring board,

the method including:

a solder forming step of forming the solder on a connecting surface ofthe connecting pad which is opposed to the metal bump and a side surfaceof the connecting pad by a plating method,

an accumulated solder forming step of melting the solder to form anaccumulated solder taking a convex shape on the connecting surface ofthe connecting pad, and

a bonding step of mounting the metal bump on the connecting surfaceprovided with the accumulated solder, to bond the accumulated solder tothe metal bump.

According to the invention, by melting the solder, it is possible tomove the solder in the portion positioned on the side surface of theconnecting pad to the connecting surface of the connecting pad with asurface tension, thereby forming the accumulated solder having a greaterthickness than a solder formed by a plating method on the connectingsurface of the connecting pad. Also in the case in which the metal bumphas a variation in a height or the case in which a warpage is generatedon the wiring board, consequently, it is possible to bond the metal bumpto the connecting pad. Therefore, it is possible to enhance anelectrical connecting reliability between the wiring board and thesemiconductor chip.

By melting the solder before bonding the metal bump to the connectingpad, moreover, it is possible to eliminate a fine void present in thesolder formed by the plating method from the solder (including theaccumulated solder), thereby causing the solder (including theaccumulated solder) to have a compact structure. Therefore, it ispossible to prevent Sn contained in the accumulated solder from beingdiffused into the electrode pad provided in the semiconductor chipthrough the metal bump at a heat treating step in a formation, on thewiring board, of a solder ball to be an external connecting terminal ofthe semiconductor device or a high temperature inspecting step of thesemiconductor device, for example.

Moreover, according to a second aspect of the invention, the solder isformed by an electrolytic plating method at the solder forming step.Consequently, it is possible to form a thicker solder than a solderformed by a nonelectrolytic plating method on the connecting surface andthe side surface in the connecting pad. Thus, it is possible to increasethe height of the accumulated solder.

Furthermore, according to a third aspect of the invention, the solder ismelted by heating the solder at a temperature which is equal to orhigher than a melting point of the solder and is lower than a heatresistant temperature of the semiconductor chip at the accumulatedsolder forming step. Consequently, it is possible to prevent thesemiconductor chip from being broken by a heat for melting the solder.

In addition, according to a forth aspect of the invention, an underfillresin forming step of forming an underfill resin to fill a clearancebetween the semiconductor chip and the wiring board after the bondingstep is included. Consequently, it is possible to increase a connectingstrength between the semiconductor chip and the wiring board.

According to the invention, it is possible to prevent the Sn containedin the solder from being diffused into the electrode pad of thesemiconductor chip through the metal bump and to enhance an electricalconnecting reliability between the wiring board and the semiconductorchip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a conventional semiconductor device,

FIG. 2 is a view (No. 1) showing a step of manufacturing theconventional semiconductor device,

FIG. 3 is a view (No. 2) showing a step of manufacturing theconventional semiconductor device,

FIG. 4 is a view (No. 3) showing a step of manufacturing theconventional semiconductor device,

FIG. 5 is a view (No. 4) showing a step of manufacturing theconventional semiconductor device,

FIG. 6 is a view (No. 5) showing a step of manufacturing theconventional semiconductor device,

FIG. 7 is a view (No. 6) showing a step of manufacturing theconventional semiconductor device,

FIG. 8 is a sectional view showing a semiconductor device according toan embodiment of the invention,

FIG. 9 is a view (No. 1) showing a step of manufacturing thesemiconductor device according to the embodiment of the invention,

FIG. 10 is a view (No. 2) showing a step of manufacturing thesemiconductor device according to the embodiment of the invention,

FIG. 11 is a view (No. 3) showing a step of manufacturing thesemiconductor device according to the embodiment of the invention,

FIG. 12 is a view (No. 4) showing a step of manufacturing thesemiconductor device according to the embodiment of the invention,

FIG. 13 is a view (No. 5) showing a step of manufacturing thesemiconductor device according to the embodiment of the invention,

FIG. 14 is a view (No. 6) showing a step of manufacturing thesemiconductor device according to the embodiment of the invention, and

FIG. 15 is a view (No. 7) showing a step of manufacturing thesemiconductor device according to the embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, an embodiment according to the invention will be described withreference to the drawings.

FIG. 8 is a sectional view showing a semiconductor device according tothe embodiment of the invention.

With reference to FIG. 8, a semiconductor device 10 according to theembodiment comprises a wiring board 11, a semiconductor chip 12, a metalbump 13, a solder 14, an accumulated solder 15, an underfill resin 16,and a solder ball 17.

The wiring board 11 has a board body 18, a via 19, a connecting pad 21,solder resists 23 and 29, a wiring 24, and a pad 25.

The board body 18 is a core substrate. A plurality of through holes 27is formed on the board body 18. As the board body 18, it is possible touse a plate-shaped resin board or a tape-like resin board, for example.

The via 19 is provided on the through holes 27. The via 19 has one ofends connected to the connecting pad 21 and the other end connected tothe wiring 24. As a material of the via 19, it is possible to use Cu,for example.

The connecting pad 21 is provided on an upper surface 18A of the boardbody 18 in a corresponding portion to a position in which the via 19 isformed. The connecting pad 21 is connected to an upper end of the via19. The connecting pad 21 has a connecting surface 21A which is opposedto the metal bump 13. As a material of the connecting pad 21, it ispossible to use Cu, for example.

The solder resist 23 is provided on the upper surface 18A of the boardbody 18. The solder resist 23 has an opening portion 23A for exposingthe connecting pads 21.

The wiring 24 is provided on a lower surface 18B of the board body 18 ina corresponding portion to the position in which the via 19 is formed.The wiring 24 is connected to a lower end of the via 19. As a materialof the wiring 24, it is possible to use Cu, for example.

The pad 25 is provided on the lower surface 18B of the board body 18.The pad 25 is connected to the wiring 24. The pad 25 serves to providethe solder ball 17 to be an external connecting terminal. As a materialof the pad 25, it is possible to use Cu, for example.

The solder resist 29 is provided on the lower surface 18B of the boardbody 18 to cover the wiring 24. The solder resist 29 has an openingportion 29A for exposing the pad 25.

The semiconductor chip 12 has a semiconductor substrate (not shown), anintegrated circuit (not shown) formed on the semiconductor substrate,and a plurality of electrode pads 31 which is electrically connected tothe integrated circuit.

The metal bump 13 is provided on the electrode pads 31. The metal bump13 has one of ends provided in contact with the connecting surface 21Aof the connecting pad 21. The metal bump 13 serves to electricallyconnect the semiconductor chip 12 to the wiring board 11. A height ofthe metal bump 13 can be set to 30 μm, for example.

The solder 14 is provided on a side surface 21B of the connecting pad21. The solder 14 is obtained as follows. A solder is formed on theconnecting surface 21A and the side surface 21B in the connecting pad 21by a plating method (see a step shown in FIG. 10 which will be describedbelow) and the solder is then molten (see a step shown in FIG. 12 whichwill be described below). At this time, the solder is not moved to theconnecting surface 21A of the connecting pad 21 but is left on the sidesurface 21B of the connecting pad 21 so that the solder 14 is obtained.As the solder 14, it is possible to use an Sn solder, an Sn—Ag solder,an Sn—Cu solder and an Sn—Ag—Cu solder, for example.

The accumulated solder 15 is provided on the connecting surface 21A ofthe connecting pad 21. The accumulated solder 15 takes a convex shape.The accumulated solder 15 is bonded to the metal bump 13. Consequently,the semiconductor chip 12 and the wiring board 11 are flip chipconnected to each other. The accumulated solder 15 is constituted by thesolder formed on the connecting surface 21A of the connecting pad 21through the plating method and any of the molten solder which isprovided on the side surface 21B of the connecting pad 21 and is movedto the connecting surface 21A of the connecting pad 21 with a surfacetension. For the solder constituting the accumulated solder 15, it ispossible to use the same solder as the solder constituting the solder14. A thickness of the accumulated solder 15 (a thickness of theaccumulated solder 15 in a portion to which the metal bump 13 is bonded)can set to 3 μm to 9 μm, for example.

Thus, the accumulated solder 15 having a greater thickness than theconventional solder 104 is provided on the connecting surface 21A of theconnecting pad 21 which is opposed to the metal bump 13. Also in thecase in which the metal bump 13 has a variation in a height or the casein which a warpage is generated on the wiring board 11, consequently, itis possible to bond the metal bump 13 to the connecting pad 21.Therefore, it is possible to enhance an electrical connectingreliability between the wiring board 11 and the semiconductor chip 12.

The underfill resin 16 is provided to fill a clearance formed betweenthe semiconductor chip 12 and the wiring board 11. The underfill resin16 serves to increase a connecting strength between the semiconductorchip 12 and the wiring board 11 (particularly, a strength of a bondingportion of the accumulated solder 15 and the metal bump 13).

The solder ball 17 is provided on the pad 25 of the wiring board 11. Thesolder ball 17 is an external connecting terminal for electricallyconnecting a mounting substrate (not shown) such as a mother board andthe semiconductor substrate 10.

According to the semiconductor device in accordance with the embodiment,the accumulated solder 15 having a greater thickness than theconventional solder 104 is provided on the connecting surface 21A of theconnecting pad 21 which is opposed to the metal bump 13. Also in thecase in which the metal bump 13 has a variation in a height or the casein which a warpage is generated on the wiring board 11, consequently, itis possible to bond the metal bump 13 to the connecting pad 21.Consequently, it is possible to enhance the electrical connectingreliability between the wiring board 11 and the semiconductor chip 12.

FIGS. 9 to 15 are views showing a process for manufacturing thesemiconductor device according to the embodiment of the invention. InFIGS. 9 to 15, the same portions as those in the semiconductor device 10according to the embodiment have the same reference numerals.

With reference to FIGS. 9 to 15, description will be given to a methodof manufacturing the semiconductor device 10 according to theembodiment. First of all, at a step shown in FIG. 9, the wiring board 11is formed by a well-known technique.

At a step shown in FIG. 10, subsequently, the solder 14 is formed on theconnecting surface 21A and the side surface 21B in the connecting pad 21by a plating method (a solder forming step). More specifically, it ispreferable to form the solder 14 through an electrolytic plating method.Thus, the solder 14 is formed by using the electrolytic plating method.As compared with the case in which a nonelectrolytic plating method isused, consequently, it is possible to increase a thickness M1 of thesolder 14. Thus, it is possible to increase a thickness of theaccumulated solder 15 formed at a step shown in FIG. 12 which will bedescribed below.

The thickness M1 of the solder 14 which is formed on the connectingsurface 21A and the side surface 21B in the connecting pad 21 can be setto 1 μm to 3 μm, for example. As the solder 14, moreover, it is possibleto use an Sn solder or an Sn based alloy solder, for example. As the Snbased alloy solder, it is possible to use an Sn—Ag solder, an Sn—Cusolder or an Sn—Ag—Cu solder, for example.

At a step shown in FIG. 11, next, the metal bump 13 is formed on theelectrode pads 31 provided on the semiconductor chip 12. The metal bump13 can be formed by the electrolytic plating method or an Au wire, forexample.

At a step shown in FIG. 12, then, the structure shown in FIG. 9 isheated to a melting point of the solder 14 or more, and the solder 14 isthus molten (remolten). Consequently, a part of the solder 14 formed onthe side surface 21B of the connecting pad 21 is collected into theconnecting surface 21A of the connecting pad 21 with a surface tensionso that the accumulated solder 15 taking a convex shape is formed on theconnecting surface 21A of the connecting pad 21 (an accumulated solderforming step). It is preferable that a temperature for melting thesolder 14 should be set to be equal to or higher than the melting pointof the solder 14 and be lower than the heat resistant temperature of thesemiconductor chip 12 (for example, 300° C.). By setting thetemperature, it is possible to prevent the semiconductor chip 12 frombeing broken by the heat for melting the solder 14.

It is preferable that a thickness M2 of the accumulated solder 15 shouldbe 3 μm to 9 μm, for example. For instance, in the case in which thethickness M1 of the solder 14 is 3 μm, the solder 14 is molten so thatthe thickness M2 of the accumulated solder 15 is set to be approximately8 μm.

Thus, the accumulated solder 15 having a greater thickness than thesolder 104 formed on the connecting pad 108 according to theconventional art is formed on the connecting surface 21A. Also in thecase in which the metal bump 13 has a variation in a height or the casein which a warpage is generated on the wiring board 11, consequently, itis possible to bond the accumulated solder 15 to the metal bump 13.Therefore, it is possible to enhance the electrical connectingreliability between the wiring board 11 and the semiconductor chip 12.

Before the metal bump 13 and the accumulated solder 15 are bonded toeach other, moreover, the solder 14 is molten. Consequently, it ispossible to eliminate a fine void present in the solder 14 formed by theplating method from the solder 14 (the solder provided on the connectingsurface 21A of the connecting pad 21) and the accumulated solder 15.Thus, the solder 14 (the solder provided on the connecting surface 21Aof the connecting pad 21) and the accumulated solder 15 have compactstructures. Therefore, the Sn contained in the accumulated solder 15 canbe prevented from being diffused into the electrode pad 31 through themetal bump 13 at a heat treating step in a formation of the solder ball17 on the pad 25 of the wiring board 11 (see FIG. 15) or a hightemperature inspecting step of the semiconductor device 10, for example.

At a step shown in FIG. 13, next, the structure shown in FIG. 12 iscleaned (for example, cleaning with pure water) and the metal bump 13 isthen mounted on the connecting surface 21A of the connecting pad 21 onwhich the accumulated solder 15 is formed, and the accumulated solder 15is thus bonded to the metal bump 13 (a bonding step).

At this time, also in the case in which the metal bump 13 has avariation in a height or the case in which the wiring board 11 has awarpage, the accumulated solder 15 is thicker than the conventionalsolder 104. Therefore, it is possible to bond the metal bump 13 to theaccumulated solder 15. Consequently, it is possible to enhance theelectrical connecting reliability between the wiring board 11 and thesemiconductor chip 12.

As a step shown in FIG. 14, subsequently, the underfill resin 16 isformed to fill the clearance between the semiconductor chip 12 and thewiring board 11 by a capillarity (an underfill resin forming step). Byforming the underfill resin 16 to fill the clearance between thesemiconductor chip 12 and the wiring board 11, thus, it is possible toincrease the connecting strength between the semiconductor chip 12 andthe wiring board 11 (particularly, the strength of the bonding portionof the accumulated solder 15 and the metal bump 13).

At a step shown in FIG. 15, then, the solder ball 17 is formed on thepad 25 in a state in which the structure shown in FIG. 14 is heated.Consequently, there is manufactured the semiconductor device 10 in whichthe semiconductor chip 12 and the wiring board 11 are flip chipconnected to each other. A fine void is not present in the solder 14 andthe accumulated solder 15 which are provided in the structure shown inFIG. 14. Therefore, the Sn contained in the solder 14 and theaccumulated solder 15 which are provided in the structure shown in FIG.14 can be prevented from being diffused into the electrode pad 31 of thesemiconductor chip 12 through the metal bump 13 through a heat treatmentat the step shown in FIG. 15.

According to the method of manufacturing the semiconductor device inaccordance with the embodiment, the accumulated solder 15 having agreater thickness than the solder 104 formed on the connecting pad 108according to the conventional art is formed on the connecting surface21A. Also in the case in which the metal bump 13 has a variation in aheight or the case in which a warpage is generated on the wiring board11, consequently, it is possible to bond the accumulated solder 15 tothe metal bump 13. Therefore, it is possible to enhance the electricalconnecting reliability between the wiring board 11 and the semiconductorchip 12.

Before the metal bump 13 and the accumulated solder 15 are bonded toeach other, moreover, the solder 14 is molten. Consequently, it ispossible to eliminate a fine void present in the solder 14 formed by theplating method from the solder 14 provided on the connecting surface 21Aof the connecting pad 21 and the accumulated solder 15. Thus, the solder14 provided on the connecting surface 21A of the connecting pad 21 andthe accumulated solder 15 have compact structures. Therefore, the Sncontained in the accumulated solder 15 can be prevented from beingdiffused into the electrode pad 31 through the metal bump 13 at a heattreating step in a formation of the solder ball 17 on the pad 25 of thewiring board 11 (see FIG. 15) or a high temperature inspecting step ofthe semiconductor device 10, for example.

While the description has been given by taking, as an example, the casein which the solder ball 17 to function as the external connectingterminal is provided in the semiconductor device 10 in the embodiment,the embodiment can also be applied to a semiconductor device which doesnot comprise the solder ball 17.

While the preferred embodiment according to the invention has beendescribed above in detail, the invention is not restricted to thespecific embodiment but various changes and modifications can be madewithout departing from the scope of the invention described in theclaims.

The invention can be applied to a method of manufacturing asemiconductor device in which a solder provided on a connecting pad of awiring board is bonded to a metal bump provided on an electrode pad of asemiconductor chip, and the semiconductor chip is thus flip chipconnected to the wiring board.

1. A method of manufacturing a semiconductor device including asemiconductor chip having a plurality of electrode pads and a wiringboard having a connecting pad formed thereon which is opposed to theelectrode pads, a metal bump formed of a first metal provided on theelectrode pads being bonded to a solder provided on the connecting pad,to flip-chip connect the semiconductor chip to the wiring board, themethod comprising: a solder forming step of forming the solder of asecond metal different from the first metal on a connecting surface ofthe connecting pad which is opposed to the metal bump and a side surfaceof the connecting pad by a plating method, the formed solder on theconnecting surface of the connecting pad and the side surface of theconnecting pad having a first thickness, an accumulated solder formingstep of melting the formed solder to provide accumulated solder on theconnecting surface of the connecting pad, said accumulated solder beingformed by a plating method and including the formed solder from the sidesurface of the connecting pad which moves to the connecting surface ofthe connecting pad by surface tension, said accumulated solder having aconvex shape and a second thickness greater than the first thickness onthe connecting surface of the connecting pad, and after forming theaccumulated solder, a bonding step of moving the metal bump toward andinto engagement with the connecting surface and with the accumulatedsolder, said accumulated solder bonding with the metal bump and cominginto contact with the bump, the connecting pad, and b1 an exposedsurface of the wiring board respectively in a surface.
 2. The method ofmanufacturing a semiconductor device according to claim 1, wherein thesolder is formed by an electrolytic plating method at the solder formingstep.
 3. The method of manufacturing a semiconductor device according toclaim 1, wherein the solder is melted at the accumulated solder formingstep by heating the solder at a temperature which is equal to or higherthan a melting point of the solder and is lower than a heat resistanttemperature of the semiconductor chip.
 4. The method of manufacturing asemiconductor device according to claim 1, further comprising: anunderfill resin forming step of forming an underfill resin to fill aclearance between the semiconductor chip and the wiring board after thebonding step.
 5. The method of manufacturing a semiconductor deviceaccording to claim 1, wherein solder on the side surface of theconnecting pad following the accumulated solder forming step has a thirdthickness that is less than the first thickness.
 6. The method ofmanufacturing a semiconductor device according to claim 1, wherein theconvex shape the accumulated solder takes during the accumulated solderforming step is different than a shape the solder takes upon forming onthe connecting pad during the solder forming step.